<!DOCTYPE html>

<html>

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>层叠</title>

    <style type="text/css">
        h3 {
            text-align: center;
        }
        
        div {
            height: 50px;
            width: 80%;
            border: 1px solid red;
            margin: auto;
        }
        
        div {
            height: 100px;
            border: 1px solid blue;
        }
        
        .wrapper {
            line-height: 100px;
            text-align: center;
        }
    </style>

</head>

<body>

    <h3>层叠(cascade)</h3>

    <div class="wrapper">
        通过这个块的样式来体会什么是CSS中的重叠
    </div>

</body>

</html>